The MERIT DEM was developed by removing multiple error components (absolute bias, stripe noise, speckle noise, and tree height bias) from the existing spaceborne DEMs (SRTM3 v2.1 and AW3D-30m v1). It represents the terrain elevations at a 3sec resolution (~90m at the equator), and covers land areas between 90N-60S, referenced to EGM96 geoid.
Hydrologically adjusted DEM is now available as a component of MERIT Hydro datasets.
Please visit MERIT Hydro webpage to get an access.
Spaceborne Digital Elevation Models (DEMs) are a fundamental input for many geoscience studies, but they still include non-negligible height errors. Here we introduce a high accuracy global DEM at 3 arcsecond resolution (~90 m at the equator) by eliminating major error components from existing DEMs (NASA SRTM3 DEM, JAXA AW3D DEM, Viewfinder Panoramas' DEM). We separated absolute bias, stripe noise, speckle noise and tree height bias using multiple satellite datasets and filtering techniques. After the error removal, land areas mapped with 2 m or better vertical accuracy were increased from 39% to 58%. Significant improvements were found in flat regions where height errors larger than topography variability, and landscapes such as river networks and hill-valley structures became clearly represented. We found the topography slope of previous DEMs was largely distorted in most of world major floodplains (e.g. Ganges, Nile, Niger, Mekong) and swamp forests (e.g. Amazon, Congo, Vasyugan). The newly developed DEM will enhance many geoscience applications which are terrain-dependent.
-- Description Paper in GRL
MERIT DEM was developed by processing the following products as baseline data (all are freely available from their web page).
- NASA SRTM3 DEM v2.1: link to the SRTM webpage
- JAXA AW3D-30m DEM v1: link to the AW3D-30m webpage
- Viewfinder Panoramas' DEM link to the ViewfinderPanoramas webpage
In addition to the above baseline DEMs, below products were used as supplementary data:
- NASA-NSIDC ICESat/GLAS GLA14 data link to the NSIDC webpage
- U-Maryland Landsat forest cover data link to the Global Forest Change webpage
- NASA Global Forest Height Data link to NASA webpage
- JAMSTEC/U-Tokyo G3WBM water body data link to G3WBM webpage
Close-up view of the MERIT DEM and the Original SRTM DEM, for the Mekong Delta and the Amazon Floodplain. Improvement by removing stripe noise, speckle noise, absolute bias, and tree height bias can be recognized.
The MERIT DEM represents elevation in [meter] , referenced to WGS84 and EGM96.
The data is prepared as 5 degree x 5 degree tiles (6000 pixel x 6000 pixel).
Filename represents the center of the lower left pixel of the data domain; e.g. the file "n30w120_dem.tif" is for the DEM of the domain N30-N35, W120-W115. (more accurately, N29.99958333-N34.99958333,W120.0004167-W115.0004167)
The 5 deg tiles are compressed into 30 degree (lat) by 30 degree (lon) package.
Package name represents the lower left corner of the package domain; e.g. the package "dem_tif_n30w120.tar" contains the files in the domain of N30-N60, W120-W090.
The data format is 'Fortran Direct Access Format' (i.e. ESRI 'FLT' raster format with the HDR file, GrADS binary with CTL file). Data is stored in 4-byte float, little endian.
GeoTiff file is also available
Use of Data
The MERIT DEM is licensed under a Creative Commons "CC-BY-NC 4.0" or Open Data Commons "Open Database License (ODbL 1.0)".
(i.e. dual license, you can choose an appropriate license for you)
To view a copy of these license, please visit:
CC-BY-NC 4.0 license: Non-Commercial Use with less restriction.
ODbL 1.0 license: Commertial Use is OK, but the derived data based on MERIT DEM should be made publicly available under the same ODbL license.
For example, if you create a flood hazard map using MERIT DEM and you'd like to provide a COMMERCIAL service based on that, you have to make the hazard map PUBLICLY AVAILABLE under OdBL license.
Note that the above license terms are applied to the "derived data" based on MERIT DEM, while they are not applied to "produced work / artwork" created with MERIT DEM (such as figures in a journal paper). The users may have a copyright of the artwork and may assign any license, if when the produced work is not considered as "derived data".
By downloading and using the data the user agrees to the terms and conditions of one of these licenses. Notwithstanding this free license, we ask users to refrain from redistributing the data in whole in its original format on other websites without the explicit written permission from the authors.
MERIT DEM is available for download at http://hydro.iis.u-tokyo.ac.jp/~yamadai/MERIT_DEM/.
The copyright of MERIT DEM is held by the developers, 2018, all rights reserved.
Data sharing policy
Citation to the paper is adequate if you simply use the MERIT DEM. If you asked help for additional handling/editing of the dataset, or your research outcome highly depends on the product, the developer would request co-authorship.
[ Citation ]
Yamazaki D., D. Ikeshima, R. Tawatari, T. Yamaguchi, F. O'Loughlin, J.C. Neal, C.C. Sampson, S. Kanae & P.D. Bates
A high accuracy map of global terrain elevations
Geophysical Research Letters, vol.44, pp.5844-5853, 2017 doi: 10.1002/2017GL072874
-- Absstract in GRL
MERIT DEM (available at http://hydro.iis.u-tokyo.ac.jp/~yamadai/MERIT_DEM)
Registration for Download
Please fill the Google Form to get an access to MERIT DEM. The password for downloading is emailed after registration.
or please contact to the developer (yamadai [at] iis.u-tokyo.ac.jp) to get an access.
Current version is v1.0.3 [15 Oct, 2018]
THe password is issued after registration on Google Form. (see above)
Licsence changed to "CC-BY-NC 4.0" or "ODbL 1.0". [v1.0.3] (15Oct, 2018)
GeoTiff compress=DEFLATE option to reduce data size. [v1.0.2]
Bug fix on the geolocation tag in GeoTiff and EHdr metadata (v1.0 was half a pixel shifted). No change in the elevation data itself. [v1.0.2] (7Mar,2018)
Improvement on surface elevations of large lakes above 60N (due to lake ice problem on AW3D) [v0.4 -> v1.0] (15May,2017)
Elevation of Grand Canyon, US (due to problem of SRTM3 elevations) [v0.4 -> v1.0] (15May,2017)
Tile package size was changed from 60deg*30deg to 30deg*30deg. (14June,2017)
NOTE: for users who have trouble in downloading large-size files, the direct link to 5deg*5deg tiles is also available: 5deg tile download page.
Sample Data (password not required)
Sample data for tiles n30w095 (N30-N35, W95-W90; Mississippi River) and n10e105 (N10-N15, E105-E110; Mekong River) is available without password. It contains both the new and original DEMs with a same data format.
ESRI EHdr format (password required): Elevation [m] (ref to EGM96)
dem_flt_n60w180.tar.gz ::: dem_flt_n60e000.tar.gz
dem_flt_n60w150.tar.gz ::: dem_flt_n60e030.tar.gz
dem_flt_n60w120.tar.gz ::: dem_flt_n60e060.tar.gz
dem_flt_n60w090.tar.gz ::: dem_flt_n60e090.tar.gz
dem_flt_n60w060.tar.gz ::: dem_flt_n60e120.tar.gz
dem_flt_n60w030.tar.gz ::: dem_flt_n60e150.tar.gz
dem_flt_n30w180.tar.gz ::: dem_flt_n30e000.tar.gz
dem_flt_n30w150.tar.gz ::: dem_flt_n30e030.tar.gz
dem_flt_n30w120.tar.gz ::: dem_flt_n30e060.tar.gz
dem_flt_n30w090.tar.gz ::: dem_flt_n30e090.tar.gz
dem_flt_n30w060.tar.gz ::: dem_flt_n30e120.tar.gz
dem_flt_n30w030.tar.gz ::: dem_flt_n30e150.tar.gz
dem_flt_n00w180.tar.gz ::: dem_flt_n00e000.tar.gz
n00w150 --no land data-- ::: dem_flt_n00e030.tar.gz
dem_flt_n00w120.tar.gz ::: dem_flt_n00e060.tar.gz
dem_flt_n00w090.tar.gz ::: dem_flt_n00e090.tar.gz
dem_flt_n00w060.tar.gz ::: dem_flt_n00e120.tar.gz
dem_flt_n00w030.tar.gz ::: dem_flt_n00e150.tar.gz
dem_flt_s30w180.tar.gz ::: dem_flt_s30e000.tar.gz
dem_flt_s30w150.tar.gz ::: dem_flt_s30e030.tar.gz
dem_flt_s30w120.tar.gz ::: dem_flt_s30e060.tar.gz
dem_flt_s30w090.tar.gz ::: dem_flt_s30e090.tar.gz
dem_flt_s30w060.tar.gz ::: dem_flt_s30e120.tar.gz
dem_flt_s30w030.tar.gz ::: dem_flt_s30e150.tar.gz
dem_flt_s60w180.tar.gz ::: dem_flt_s60e000.tar.gz
s60w150 --no land data-- ::: dem_flt_s60e030.tar.gz
s60w150 --no land data-- ::: dem_flt_s60e060.tar.gz
dem_flt_s60w090.tar.gz ::: dem_flt_s60e090.tar.gz
dem_flt_s60w060.tar.gz ::: dem_flt_s60e120.tar.gz
dem_flt_s60w030.tar.gz ::: dem_flt_s60e150.tar.gz
GeoTiff format (password required): Elevation [m] (ref to EGM96)
dem_tif_n60w180.tar ::: dem_tif_n60e000.tar
dem_tif_n60w150.tar ::: dem_tif_n60e030.tar
dem_tif_n60w120.tar ::: dem_tif_n60e060.tar
dem_tif_n60w090.tar ::: dem_tif_n60e090.tar
dem_tif_n60w060.tar ::: dem_tif_n60e120.tar
dem_tif_n60w030.tar ::: dem_tif_n60e150.tar
dem_tif_n30w180.tar ::: dem_tif_n30e000.tar
dem_tif_n30w150.tar ::: dem_tif_n30e030.tar
dem_tif_n30w120.tar ::: dem_tif_n30e060.tar
dem_tif_n30w090.tar ::: dem_tif_n30e090.tar
dem_tif_n30w060.tar ::: dem_tif_n30e120.tar
dem_tif_n30w030.tar ::: dem_tif_n30e150.tar
dem_tif_n00w180.tar ::: dem_tif_n00e000.tar
n00w150 --no land data-- ::: dem_tif_n00e030.tar
dem_tif_n00w120.tar ::: dem_tif_n00e060.tar
dem_tif_n00w090.tar ::: dem_tif_n00e090.tar
dem_tif_n00w060.tar ::: dem_tif_n00e120.tar
dem_tif_n00w030.tar ::: dem_tif_n00e150.tar
dem_tif_s30w180.tar ::: dem_tif_s30e000.tar
dem_tif_s30w150.tar ::: dem_tif_s30e030.tar
dem_tif_s30w120.tar ::: dem_tif_s30e060.tar
dem_tif_s30w090.tar ::: dem_tif_s30e090.tar
dem_tif_s30w060.tar ::: dem_tif_s30e120.tar
dem_tif_s30w030.tar ::: dem_tif_s30e150.tar
dem_tif_s60w180.tar ::: dem_tif_s60e000.tar
s60w150 --no land data-- ::: dem_tif_s60e030.tar
s60w150 --no land data-- ::: dem_tif_s60e060.tar
dem_tif_s60w090.tar ::: dem_tif_s60e090.tar
dem_tif_s60w060.tar ::: dem_tif_s60e120.tar
dem_tif_s60w030.tar ::: dem_tif_s60e150.tar